// SPDX-License-Identifier: GPL-2.0/* * Raspberry Pi 4 firmware reset driver * * Copyright (C) 2020 Nicolas Saenz Julienne <nsaenzjulienne@suse.de> */#include <linux/delay.h>#include <linux/device.h>#include <linux/module.h>#include <linux/of.h>#include <linux/platform_device.h>#include <linux/reset-controller.h>#include <soc/bcm2835/raspberrypi-firmware.h>#include <dt-bindings/reset/raspberrypi,firmware-reset.h> struct rpi_reset {	struct reset_controller_dev rcdev;	struct rpi_firmware *fw;}; static inline struct rpi_reset *to_rpi(struct reset_controller_dev *rcdev){	return container_of(rcdev, struct rpi_reset, rcdev);} static int rpi_reset_reset(struct reset_controller_dev *rcdev, unsigned long id){	struct rpi_reset *priv = to_rpi(rcdev);	u32 dev_addr;	int ret; 	switch (id) {	case RASPBERRYPI_FIRMWARE_RESET_ID_USB:		/*		 * The Raspberry Pi 4 gets its USB functionality from VL805, a		 * PCIe chip that implements xHCI. After a PCI reset, VL805's		 * firmware may either be loaded directly from an EEPROM or, if		 * not present, by the SoC's co-processor, VideoCore. rpi's		 * VideoCore OS contains both the non public firmware load		 * logic and the VL805 firmware blob. This triggers the		 * aforementioned process.		 *		 * The pci device address is expected is expected by the		 * firmware encoded like this:		 *		 *	PCI_BUS << 20 | PCI_SLOT << 15 | PCI_FUNC << 12		 *		 * But since rpi's PCIe is hardwired, we know the address in		 * advance.		 */		dev_addr = 0x100000;		ret = rpi_firmware_property(priv->fw, RPI_FIRMWARE_NOTIFY_XHCI_RESET,					    &dev_addr, sizeof(dev_addr));		if (ret)			return ret; 		/* Wait for vl805 to startup */		usleep_range(200, 1000);		break; 	default:		return -EINVAL;	} 	return 0;} static const struct reset_control_ops rpi_reset_ops = {	.reset	= rpi_reset_reset,}; static int rpi_reset_probe(struct platform_device *pdev){	struct device *dev = &pdev->dev;	struct rpi_firmware *fw;	struct device_node *np;	struct rpi_reset *priv; 	np = of_get_parent(dev->of_node);	if (!np) {		dev_err(dev, "Missing firmware node\n");		return -ENOENT;	} 	fw = devm_rpi_firmware_get(&pdev->dev, np);	of_node_put(np);	if (!fw)		return -EPROBE_DEFER; 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);	if (!priv)		return -ENOMEM; 	dev_set_drvdata(dev, priv); 	priv->fw = fw;	priv->rcdev.owner = THIS_MODULE;	priv->rcdev.nr_resets = RASPBERRYPI_FIRMWARE_RESET_NUM_IDS;	priv->rcdev.ops = &rpi_reset_ops;	priv->rcdev.of_node = dev->of_node; 	return devm_reset_controller_register(dev, &priv->rcdev);} static const struct of_device_id rpi_reset_of_match[] = {	{ .compatible = "raspberrypi,firmware-reset" },	{ /* sentinel */ }};MODULE_DEVICE_TABLE(of, rpi_reset_of_match); static struct platform_driver rpi_reset_driver = {	.probe	= rpi_reset_probe,	.driver	= {		.name = "raspberrypi-reset",		.of_match_table = rpi_reset_of_match,	},};module_platform_driver(rpi_reset_driver); MODULE_AUTHOR("Nicolas Saenz Julienne <nsaenzjulienne@suse.de>");MODULE_DESCRIPTION("Raspberry Pi 4 firmware reset driver");MODULE_LICENSE("GPL");